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Posted: October 16, 2007

New nanotechnology wastewater treatment system for removing heavy metals

(Nanowerk News) The presence in the environment of large quantities of toxic metals such as mercury, lead, cadmium, zinc or others, poses serious health risks to humans, and this threat puts the scientific community under pressure to develop new methods to detect and eliminate toxic contaminants from wastewaters in efficient and economically viable ways.

Resulting from the combination of water treatment investigations with the latest in material science, a new type of nanomaterial called nanostructured silica has been found to fulfil the requisites necessary for these applications.

With its large surface area and regular pores, it is an ideal material that after a functionalization process that links to its surface diverse organic ligands has the capability of being able to extract heavy metals from wastewaters. This capacity also allows its use as a high sensitivity detection tool for these toxic metals, and considering that the contamination levels permitted in drinking water are increasingly restrictive; functionalized silica offers additional benefits over other water treatment methods.

The design of this nanostructured functionalized silica is based on the emulation on the material of the reaction that heavy metals have with some biomolecules in living cells. Therefore a good understanding of the reaction that bonds such metals to particular functional groups on living cells is of great use to determine the best functional groups to be used on the surface of the nanostructured material; for example, it has been detected that heavy metals interact mainly with functional groups containing oxygen, nitrogen and sulphur.

Following the same line of thinking, the researchers from the URJC, managed by Doctor Isabel Sierra, have achieved a great improvement in heavy metal absorption by creating new materials using different types of silica such as MCM-41 and HMS and modified them with 5-mercapto-1-methylthiazole making them capable of collecting lead and zinc. Their study has also demonstrated that the prepared materials are capable of several cycles of absorption/desorption. With the added benefit that the retained materials can be recovered and then reused, and this has important economical benefits for industry and society.

This investigation has been published on the latest releases of Journal of Separation Science and Journal of Colloid Interface Science.